Vibrating structure gyroscopes detect rotation by sensing changes in the vibration of a vibrating structure such as a resonator. Typically, the resonator is induced to vibrate by some mechanism. Rotation of the vibrating resonator can cause changes in the vibration (e.g., angle, speed). These changes can be detected and used to determine the rotation of the resonator. Vibrating structure gyroscopes typically include piezoelectric, hemispherical, tuning fork, and wheel-type gyroscopes.
Hemispherical type vibrating structure gyroscopes can include a resonator having a hemispherical shell attached to a stem. The stem of the resonator is mounted to a structure, and the resonator can vibrate about the stem. These types of gyroscopes can be made using conventional high-precision machining techniques. It is typically desirable to build this type of gyroscope using micromachining techniques, allowing batch fabrication of many gyroscopes at one time.
In some examples, the uniformity of the hemispherical shell can affect the accuracy with which the vibrations in the hemispherical shell can be used to detect rotation. In addition, the positioning of the stem on the hemispherical shell (e.g., if the stem is off centered) can also affect the accuracy of the gyroscope. Thus, precision in the manufacture of the hemispherical type gyroscope is an important factor that can be difficult to achieve.